Microscopy and Magnification PDF

MICROSCOPY WHAT IS A MICROSCOPE? A microscope is an instrument that allows scientists to observe objects that are too small to be seen with the naked eye.  TYPES OF MICROSCOPES Light microscopes (optical microscopes) - uses visible light to generate magnified images Electron microscopes -...

MICROSCOPY WHAT IS A MICROSCOPE? A microscope is an instrument that allows scientists to observe objects that are too small to be seen with the naked eye.  TYPES OF MICROSCOPES Light microscopes (optical microscopes) - uses visible light to generate magnified images Electron microscopes - uses a beam of electrons as a source of illumination  KEY WORDS Magnification – enlarges the appearance of an object, making it look bigger than its actual size Resolution – the ability of a microscope to distinguish between two objects close together as separate Magnification makes things look larger, resolution makes things clearer! (improves clarity)  LIGHT MICROSCOPES Ideal for viewing live cells and tissues and large cellular structures like nucleus or chloroplast Easy to use, can view live specimens and is inexpensive Low magnification and lower resolution – can’t view smaller organelles like ribosomes or membrane structures  ELECTRON MICROSCOPES Much higher magnification and higher resolution Cant view live specimens, expensive and requires expertise to operate IDENTIFY TWO KEY DIFFERENCES BETWEEN LIGHT AND ELECTRON MICROSCOPES Electron microscopes are a lot more expensive Light microscopes allow you to see colour, electron microscopes shows black and white Specimens must be dead to view under an electron microscope but in a light microscope they can be alive or dead Electron microscopes have greater resolution Electron microscopes have greater magnification Help box Think of cost, resolution and magnification, types of specimens used  1. Fine focus Base 2. 7 Diaphragm. High power objective lens 3 8.. Low and medium power 4. 9 objective Lens. 5 Stage clips. 10 Coarse focus 6. Stage. Eyepiece lens (10x) Arm 11 Light source. CALCULATING MAGNIFICATION ▪ You may get asked to work out how many times something has been magnified ▪ Or what it’s actual size is  https://www.youtube.com/watch?v=AKvp2PvBvo4 Writing a number in standard form always has the same format A number between 1 -9 x10 ? Never changes What you need to work out (1-9) x10 ? WRITING BIG NUMBERS Eg. 1 million = 10,00000 All numbers in standard form have to be between 1 and 9 (can’t have double digits) 10,00000.00 has to become 1x10? Count how many times the decimal point moves in 10,00000.00 to 1.00 In standard form = 1.0X106 Or 1 000 000 000 000 000 000 000 000 000 (can you imagine having to write all those 0s all the time??) In standard form = 1.0X1027